@thibaultmilan the business model, I'm sure, is marketing. It's just a way for them to insert you into one of their marketing funnels. Either way, it's a great initiative and as long as it remains free; big kudos to them.

Okay so let me get this right. Essentially speaking, this is like WeTransfer except that it encrypts your files yes? I am intrigued, but I do have to admit that with all the hype around encryption and encryption based apps, what exactly do you offer in terms of privacy?
I like the fact that each link that's generated expires automatically so that it can't remain a permanent resident of the inter-webs, but how exactly is my anonymity protected if say someone I did not intend to share it with finds the link somewhere, somehow?
We obviously can't get enough of free file sharing tools and your twist does sound like a twist but perhaps more detail in the workings behind it would clear some things up.
You have my upvote tough!

@fouad_tolaib About your part on the link landing in inappropriate hands, Send by Firefox allows only one download. Once it's downloaded, it looks like the link being used by the same person or others would result in an error.

Great product, keep up the good work. I personally think that it would have been much better if we could send the file to targeted users from the platform itself. Creating a private friend circle solves the problem of random people downloading files from the link.
Or you should let the user select the time - when the link should expire. So that the user can know that no one else can access the file in such a short period of time.
Or you should enable double authentication, once the end user clicks on the link he/she received from the other friend, the web portal should ask for some type of password or code which the file owner received via e-mail when the end user opened the link.
How do you promise good downloading/uploading speed in different countries and regions?

A free, encrypted, ad-free WeTransfer alternative? Yes, please.
The only limit might be this 1 day/1 click limit. Might not be the best thing for clients/teammates/stakeholders that are slower to check their emails or that are not focused on your project that day.